The present invention relates to an inkjet head that ejects an ink from a plurality of ejection outlets by pressure generated by a piezoelectric element when a drive element drives the piezoelectric element through a wiring board.
In an inkjet printer, color printing is performed using a plurality of ink cartridges, such as cyan, magenta, yellow and black cartridges, and inks supplied from a plurality of ink cartridges are ejected from a plurality of ejection outlets formed in the inkjet head by pressure generated by a piezoelectric element. The piezoelectric element generates pressure according to a drive voltage supplied from a driving IC, and the drive voltage from the driving IC is supplied to the piezoelectric element through a flexible wiring board.
The flexible wiring board is constructed by providing a plurality of wires on one or both surfaces of an insulating film. Using the flexible wiring board for the transmission of a drive voltage, a control signal, etc. is advantageous because it is possible to increase the degree of freedom in mounting an inkjet head in an inkjet printer and decrease the size of the inkjet printer. In recent years, a COF (Chip On Film) comprising a driving IC mounted directly on a flexible wiring board has been put into practical use. Since the COF can shorten the distance from the driving IC to the piezoelectric element, it is possible to reduce the attenuation and delay of the drive voltage, and it is possible to efficiently drive the piezoelectric element.
In a connection structure of a flexible wiring board disclosed in Japanese Patent Application Laid-Open No. 2004-114609, a plurality of terminal lands and wires are formed on one surface of a band-shaped insulating body, through-holes for exposing the terminal lands from the other side are formed in the insulating body, and the terminal section of the piezoelectric element of the inkjet head and the terminal land are connected by solder through the through-hole. In other words, the solder is deposited only on the terminal lands exposed at the other side of the insulating body. Thus, since the terminal lands and the wires on one surface are isolated from the solder by the insulating body, a short circuit of wires due to leakage of solder will never occur.